This invention concerns an isotonic cleansing agent and method for use in electronic instrumentation systems for determining hematological components of blood samples. It is especially suitable for use in semi-automated and automated systems designed for electronic enumeration and sizing of blood cells, detection of hemoglobin and their collective indices, platelet parameters and lymphoid-myeloid populations of leukocytes in a single blood sample. The cleanser comprises a water solution of chemical salts, providing an electrolytic solution capable of conducting current, and a non-hemolytic detergent suitable for cleansing sensing apertures and associated fluid pathways within the instrument system.
Certain classical determinations are commonly made on patient blood samples to provide medical baseline or diagnostic information to the attending physician in order to assist in the proper diagnosis and treatment of disease. These include the red blood cell count (RBC), the hematocrit (HCT), the hemoglobin (HGB), the mean corpuscular volume (MCV), the mean corpuscular hemoglobin (MCH), the mean corpuscular hemoglobin concentration (MCHC), the platelet count (PLT), the mean platelet volume (MPV), the white blood cell count (WBC) and, more recently, the relative lymphoid and myeloid populations comprising the total white blood cell count.
Much effort has been devoted to the development of satisfactorily automated leukocyte differential systems, especially one that is easily adaptable to automatic blood counting instruments. In particular, it is desirable to develop reagents and methods for use with the Coulter Counter.RTM. Model S-Plus automated blood counter, manufactured by Coulter Electronics, Inc. of Hialeah, Fla., which will enable the cell volume data accumulated on a Coulter Channelyzer.RTM. particle size analyzer to discriminate two populations of leukocytes: (1) a lymphoid (lymphocyte series) population, and (2) a myeloid (granulocyte series) population. Such data are useful as a screening tool for spotting abnormal leukocyte ratios. Abnormal situations flagged out by this method give information of diagnostic significance, and for further study.
Satisfactory performance of any of the counting and sizing features of automated hematology using electronic pulse spectrometry is dependent on maintaining clean and unimpeded fluid pathways, especially in and near the sensing apertures. Due to the small size of the aperture and the inaccessability of much of the fluid path, it is necessary to use a fluid cleansing agent in order to reach every part of the fluid system to clean away deposits and prevent buildup of minerals and especially protein from the blood samples.
The cleansing agent must meet several criteria to be usable in an enclosed automated blood counting system. Primarily, the agent must be chemically fast and effective, but not so strong as to damage glass and plasticware upon extended contact. Secondarily, the agent should be: (a) isotonic so as to be isoconductive with the blood diluent being used; (b) it must be fully compatible with the diluent so as not to cause any chemical or physical decomposition creating interfering debris in or near the sensing apertures; (c) it should not be hemolytic or overly destructive towards blood cells, since traces of it may remain in the fluid pathways even after flushing with the blood diluent; (d) it should be visually distinguishable from the blood cell diluent by color, density or some other easily visible property.